Gone are the days of carrying around flash drives and panicking when the office server is full. Online document storage has become the easiest and quickest way for sharing information that can be securely accessed from anywhere within a company.

Dozens of service providers offer cloud-based file sharing and storage, but Natick, Mass.-based Nasuni provides a new breed of storage and sharing that combines on-premises hardware with encrypted cloud-based primary storage. Its unlimited storage capability appeals to companies with multiple sites that need access to the same files.

Andres Rodriquez, Nasuni CEO and co-founder, was formerly the chief technology officer at The New York Times, where he archived its digital content.

"For years the traditional storage controller has been a game of RAM and disk. Put the cloud inside and what you have is a third component," he says.

While cloud storage can do great things, it also comes with its own set of challenges. "It's hard for everyday business use," says Connor Fee, Nasuni's director of marketing. There is also no guarantee the data will be completely secure, which is crucial for engineering and construction firms working on proprietary virtual building files.

The four-year-old Nasuni has 100 clients around the globe, particularly in the architecture, engineering, construction, legal and education industries.

The Walsh Group, a Chicago-based heavy, civil and transportation contractor, started using Nasuni two years ago to share files and information among its 14 offices across North America. Walsh recently added Nasuni's mobile app to its employees' iPhones and iPads to further enhance connectivity.

Walsh is in the early stages of constructing the new Ohio River bridges between Louisville, Ky., and southern Indiana. Mike Driscoll, the firm's infrastructure architect, was initially attracted to Nasuni for archiving jobsite data. However, Nasuni's unique security feature was a key selling point when he shopped cloud-service providers.

"We must consider the consequences of an employee of that provider either negligently or maliciously exposing sensitive corporate and personal information," Driscoll says.

With Nasuni, the data is protected by an encryption key before it leaves the customer's building, and not even Nasuni can access it. "We alone have access to that key, thereby ensuring that no one else has access to our data, regardless of where it may sit," Driscoll adds.

Once the data is protected, there's no need for copies or backups, which would require additional cost and time. In fact, "these multi-terabyte systems are designed to not be backed up—as labor intensive as that would be," Fee says.

Other cloud-storage providers such as YouSendIt and Dropbox allow users to send files between people and devices without using email. Riverbed's Whitewater, which replaces the tape system that companies use for backups, does not replace a traditional file server. Meanwhile, Microsoft recently purchased Storsimple, offering a service similar to Nasuni's with a comparable level of security. However, it does not have the same replication features.

Amazon's gateway storage service also doesn't offer the replication technology or mobile access that makes Nasuni attractive to distributed enterprise firms, experts say.

A Nasuni subscription runs about $8,000 per terabyte per year.